The location of a mobile, wireless or wired device is a useful and sometimes necessary part of many services. A Location Information Server (“LIS”) may be responsible for providing location information to such devices with an access network. The LIS may utilize knowledge of the access network and its physical topology to generate and serve location information to devices.
The LIS, in general terms, is a network node originally defined in the National Emergency Number Association (“NENA”) i2 network architecture addressing a solution for providing E-911 service for users of Voice over Internet Protocol (“VoIP”) telephony. In VoIP networks, the LIS is the node that determines the location of the VoIP terminal. Beyond the NENA architecture and VoIP, the LIS is a service provided by an access network provider to supply location information to users of the network by utilizing knowledge of network topology and employing a range of location determination techniques to locate devices attached to the network. The precise methods used to determine location are generally dependent on the type of access network and the information that can be obtained from the device. For example, in a wired network, such as Ethernet or DSL, a wiremap method is commonplace. In wiremap location determination, the location of a device may be determined by finding which cables are used to send packets to the device. This involves tracing data through aggregation points in the network (e.g., Ethernet switches, DSL access nodes) and finding the port for which packets are sent to the device. This information is combined with data available to the LIS (generally extracted from a database) to determine a final location of the device.
In wireless networks, a range of technologies may be applied for location determination, the most basic of which uses the location of the radio transmitter as an approximation. The Internet Engineering Task Force (“IETF”) and other standards forums have defined various architectures and protocols for acquiring location information from an LIS. In such networks, an LIS may be automatically discovered and location information retrieved using network specific protocols. Location information may be retrieved directly or the LIS may generate temporary uniform resource identifiers (“URI”) utilized to provide location indirectly (i.e., location URI). Geodetic, civic positions and location URIs for a mobile device may be determined as a function of location information from the LIS. A request for geodetic and/or civic locations may provide location information at the time the location request is made. A location URI may generally be passed to another party which can utilize it to retrieve the target device's location at a later time, typically from the same location server that provided the location URI.
A few exemplary wireless networks are a World Interoperability for Microwave Access (“WiMAX”) network and a Long Term Evolution (“LTE”) network. Generally, WiMAX is intended to reduce the barriers to widespread broadband access deployment with standards-compliant wireless solutions engineered to deliver ubiquitous fixed and mobile services such as Voice over IP (“VoIP”), messaging, video, streaming media, and other IP traffic. WiMAX enables delivery of last-mile broadband access without the need for direct line of sight. Ease of installation, wide coverage, and flexibility makes WiMAX suitable for a range of deployments over long-distance and regional networks, in addition to rural or underdeveloped areas where wired and other wireless solutions are not easily deployed and line of sight coverage is not possible.
LTE is generally a 4G wireless technology and is considered the next in line in the GSM evolution path after UMTS/HSPDA 3G technologies. LTE builds on the 3GPP family including GSM, GPRS, EDGE, WCDMA, HSPA, etc., and is an all-IP standard like WiMAX. LTE is based on orthogonal frequency division multiplexing (“OFDM”) Radio Access technology and multiple input multiple output (“MIMO”) antenna technology. LTE provides higher data transmission rates while efficiently utilizing the spectrum thereby supporting a multitude of subscribers than is possible with pre-4G spectral frequencies. LTE is all-IP permitting applications such as real time voice, video, gaming, social networking and location-based services. LTE networks may also co-operate with circuit-switched legacy networks and result in a seamless network environment and signals may be exchanged between traditional networks, the new 4G network and the Internet seamlessly.
The original version of the standard on which WiMAX is based (IEEE 802.16) specified a physical layer operating in the 10 to 66 GHz range. 802.16a, updated in 2004 to 802.16-2004, added specifications for the 2 to 11 GHz range. 802.16-2004 was updated by 802.16e-2005 in 2005 and uses scalable orthogonal frequency division multiple access (“SOFDMA”) as opposed to the OFDM version with 256 sub-carriers (of which 200 are used) in 802.16d. More advanced versions, including 802.16e, also bring Multiple Antenna Support through MIMO functionality. This brings potential benefits in terms of coverage, self installation, power consumption, frequency re-use and bandwidth efficiency. Furthermore, 802.16e also adds a capability for full mobility support. Most commercial interest is in the 802.16d and 802.16e standards, since the lower frequencies used in these variants suffer less from inherent signal attenuation and therefore gives improved range and in-building penetration. Already today, a number of networks throughout the world are in commercial operation using WiMAX equipment compliant with the 802.16d standard.
The WiMAX Forum has provided an architecture defining how a WiMAX network connects with other networks, and a variety, of other aspects of operating such a network, including address allocation, authentication, etc. It is important to note that a functional architecture may be designed into various hardware configurations rather than fixed configurations. For example, WiMAX architectures according to embodiments of the present subject matter are flexible enough to allow remote/mobile stations of varying scale and functionality and base stations of varying size. The art of WiMAX and LTE subscriber station (SS) location, however, is still in its infancy, and the current standards do not define how to solve the WiMAX and LTE location problems using network measurement messages utilized by the respective networks for normal operation. Thus, there is a need in the art to overcome the limitations of the prior art and provide a novel system and method for locating WiMAX and LTE subscriber stations.
One embodiment of the present subject matter provides a method for estimating a location of a subscriber station receiving a first signal from a first base station and receiving a second signal from a second base station where the first and second base stations are nodes in a WiMAX or LTE network. The method may comprise receiving from the subscriber station a message containing a first information and a second information, and determining a range ring from the first base station using the first information. A location hyperbola may be determined using the second information wherein the location hyperbola has the first and the second base stations as foci. A location of the subscriber station may then be estimated using the range ring and location hyperbola.
Another embodiment of the present subject matter may provide a method for estimating a location of a subscriber station receiving a first signal from a first base station, receiving a second signal from a second base station, and receiving a third signal from a third base station where the first, second, and third base stations are nodes in a WiMAX or LTE network. The method may comprise receiving from the subscriber station a message containing a first information and a second information, and determining a range ring from the first base station using the first information. A location hyperbola may be determined using the second information wherein the location hyperbola has the second and the third base stations as foci. A location of the subscriber station may then be estimated using the range ring and the location hyperbola.
A further embodiment of the present subject matter provides a method for estimating a location of a subscriber station receiving a signal from a base station where the base station is a node in a WiMAX or LTE network. The method may comprise receiving from said subscriber station a message containing a first information and a second information, and determining a range ring from the base station using the first information. A serving sector of the base station may be determined for the subscriber station, and plural sub-sectors determined for the serving sector. From the second information a carrier-to-interference noise ratio (“CINR”) may be determined for each of a first and a second neighboring sector to the serving sector. A most likely sub-sector may also be determined from the plural sub-sectors based on a comparison of the CINR for the first and second neighboring sectors. A location of the subscriber station may then be estimated as a point of intersection of the range ring and a bisector of the most likely sub-sector.
One embodiment of the present subject matter provides a method for estimating a location of a subscriber station operating in a wireless network. The method may comprise the steps of transmitting from a network location device to a first base station a request for network measurement data, and transmitting from the first base station to the subscriber station a message to trigger the subscriber station to scan the wireless network. A scanning result message containing information characterizing the first base station and a second base station may be transmitted from the subscriber station to the first base station, and information from the scanning result message transmitted from the first base station to the network location device. A location for the subscriber station may then be estimated at the network location device based at least on the information from the scanning result message.
A further embodiment of the present subject matter provides a system for estimating a location of a subscriber station receiving a first signal from a first base station and receiving a second signal from a second base station where the first and second base stations are nodes in a WiMAX or LTE network. The system may include a receiver for receiving from the subscriber station a message containing a first information and a second information, and circuitry for determining a range ring from the first base station using the first information. The system may also include circuitry for determining a location hyperbola using the second information wherein the location hyperbola has the first and second base stations as foci. The system may include circuitry for estimating a location of the subscriber station using the range ring and the location hyperbola.
Another embodiment of the present subject matter provides a system for estimating a location of a subscriber station receiving a first signal from a first base station, receiving a second signal from a second base station, and receiving a third signal from a third base station where the first, second, and third base stations are nodes in a WiMAX or LTE network. The system may comprise a receiver for receiving from the subscriber station a message containing a first information and a second information, and circuitry for determining a range ring from the first base station using the first information. The system may also comprise circuitry for determining a location hyperbola using the second information wherein the location hyperbola has the second and third base stations as foci. The system may comprise circuitry for estimating a location of the subscriber station using the range ring and location hyperbola.
Yet another embodiment of the present subject matter provides a system for estimating a location of a subscriber station receiving a signal from a base station where the base station is a node in a WiMAX or LTE network. The system may comprise a receiver for receiving from the subscriber station a message containing a first information and a second information, and circuitry for determining a range ring from the base station using the first information. The system may also include circuitry for determining a serving sector of the base station for the subscriber station, and circuitry for determining plural sub-sectors for the serving sector. The system may include circuitry for determining from the second information a CINR for each of a first and a second neighboring sector to the serving sector, and circuitry for determining a most likely sub-sector from the plural sub-sectors based on a comparison of the CINR for the first and second neighboring sectors. The system may further include circuitry for estimating a location of the subscriber station as a point of intersection of the range ring and a bisector of the most likely sub-sector.
One embodiment of the present subject matter provides a system for estimating a location of a subscriber station operating in a wireless network. The system may include a network location device including a first transmitter for transmitting to a first base station a request for network measurement data where the first base station includes a second transmitter to transmit to the subscriber station a message to trigger the subscriber station to scan the wireless network. The subscriber station may include a third transmitter to transmit to the first base station a scanning result message containing information characterizing the first base station and a second base station. The first base station may include a fourth transmitter to transmit to the network location device information from the scanning result message. The system may also include circuitry for estimating at the network location device a location for the subscriber station based at least on the information from the scanning result message.
These embodiments and many other objects and advantages thereof will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the embodiments.